What is the predominant source of tear lipids?

• A. Lacrimal glands
• B. Corneal epithelium
• C. Meibomian glands
• D. Conjunctival goblet cells

Answer: (C)

The lipid portion of the tear film comes predominantly from the Meibomian glands, which are specialized sebaceous glands located in the eyelid margins. They secrete a lipid-rich substance called meibum that forms the outer lipid layer on top of the aqueous tear layer, reducing evaporation and helping to stabilize the tear film. The aqueous component of tears is produced mainly by the lacrimal glands, while mucins from conjunctival goblet cells contribute to the mucous layer; the corneal epithelium does not secrete tear lipids. When Meibomian gland function is impaired, the lipid layer thins, evaporation increases, and tear film stability decreases, leading to evaporative dry eye.